5/9/2012. “What are those beautiful yellow flowers we saw growing alongside the interstate?” It’s a question we often hear this time of year from out-of-state visitors. The answer, of course, is Scotch broom. (also known as Scot’s broom) But when the conversation turns to how pretty this flowering shrub would look in their own garden back home, they are amazed to discover that Scotch broom is considered a Class B Noxious Weed in Washington State.
Native to Europe and North Africa, Scotch broom was first introduced as an ornamental into Pacific NW coastal gardens in the late 1800’s. Later, the hardy shrub was used for erosion control along public roads. From there, it spread quickly into dunes, prairies, upland meadows, and other natural areas.
Unfortunately, for those of us who live in the Northwest, Scotch broom is a prolific seed producer and very aggressive. The bushes form dense stands which squeeze out native plants and so can have a devastating impact on local wildlife habitat. They are also drought-tolerant, thrive in poor soils, and have a nasty tendency to resprout even after the shrubs have been cut down. Think of them as the woody version of a dandelion.
Scotch broom is an upright shrub that grows 3-10 feet tall. During spring and early summer, they are covered in a profusion of bright yellow blossoms that are a delight to see. (for a close-up photo, please check the King County website) But don’t make the mistake of planting one in your back yard! Like a field full of dandelions, they are almost impossible to get rid of once they’ve gone to seed.